This january, i purchased a top cover from LektroiD here on this forum (thanks again, mate) and promised him to publish some pictures from my restoration of a juno-106 (replacing faulty wave-chips, voice-chips and quite a lot of other stuff).

I will try to put images and text in this thread later today and hopefully it will help someone else doing what i did. I am i no way a soldering expert but taking it slowly and methodically (and having a small enough soldering-iron) will definately help.

Why did i undertake this operation to begin with? First of all, two of my voices did not work. The sub-osc did not work either, nor did the white noice. I got the juno off Ebay from a german seller and it had seen better days (to say the least). The top-cover was very rusty (not kidding) and most things were loose (bender board for example). I had one of these over 20 years ago which i bought almost new with its original casing, etc. When the D50 arrived i went digial all the way and sold it (which i have regretted since). I then found this and purchased it, not knowing exactly what i was in for.....

The first thing i did was to extract the main board where the voice and wave chips are. There are 6 voice chips and 3 wave chips:

(Voice-W-Voice-Voice-W-Voice-Voice-W-Voice) counting the rightmost voice chip as number #1, etc (from right to left, 1 to 6)

After doing the same for the other voice chip and the faulty Wave-chip (which was the cause of the missing sub-osc) it was time to swap the old rusty cover for the new one that i purchased from LektroiD.

The wave chip is actually a clone from D'naab (tried Roland but original Wave chips seems to be extremely difficult to get hold of. As for the voice chips, Roland Sweden apparently found a full bucket of them (yes, no kidding) in a closet where they had been for many years unnoticed). Here is a closeup of the voice+wave soldered on:

In the mean-time i try to figure out how to fix the white-noice problem. Do anyone have a clue what would be the best starting point in trying to narrow down where the problem actually is? I also still have a slight "thunder" still (or should i say static?) which i don't believe has anything to do with faulty voice-chips. Do you guys have any hints or tips to share?

I would definitely look at replacing as many electrolytic caps as possible, starting with the biggest ones in the PSU.
This synth would be at least 20years old, and all the electrolytics would be drying out by now. Dodgy caps means dirty power rails, and when the big ones in the PSU get dry you end up with power rails which simply fail to deliver smooth, responsive power. This leads to transients being compromised and an increased noise level all round.
I know someone who has an M1 which recently became chronically distorted. Replacing 20 or so electrolytics (including the biggest PSU ones) has not only fixed the immediate problem, but has given it a "clearer, more dynamic sound than it has had for years." (This guy plays it live quite regularly)_________________What makes a space ours, is what we put there, and what we do there.

I would definitely look at replacing as many electrolytic caps as possible, starting with the biggest ones in the PSU.
This synth would be at least 20years old, and all the electrolytics would be drying out by now. Dodgy caps means dirty power rails, and when the big ones in the PSU get dry you end up with power rails which simply fail to deliver smooth, responsive power. This leads to transients being compromised and an increased noise level all round.
I know someone who has an M1 which recently became chronically distorted. Replacing 20 or so electrolytics (including the biggest PSU ones) has not only fixed the immediate problem, but has given it a "clearer, more dynamic sound than it has had for years." (This guy plays it live quite regularly)

Hi Uncle Krunkus,

That is indeed a good advice. I have replaced a bunch of capacitors on one of my old pc-mainboards (where the fluid leaked out at the top, causing the computer to re-boot sporadically) so it should be doable.

Hmmmm... time to open it up again and write down a shopping list for caps...

Remember that the most important part is the value (uF)
You can use caps which are over rated for voltage (ie, if the original is 25V you can use that voltage or higher, not lower)
Keep in mind that if you have to go for a replacement with a very much greater voltage rating, you need to check that it will still physically fit into the space provided.
Try to get the pitch of the leads the same, but this is not critical.
There are newer "Low ESR" caps which could even make the de-coupling better than it was originally.
I'm thinking of doing my D50 soon. It's of (almost) the same vintage._________________What makes a space ours, is what we put there, and what we do there.

I have but unfortunately nothing is heard besides a very slight change of "something" noice-like in the background. I have tried two different panel boards so i am pretty confident that the problem is elsewhere.

I did order two BA662's from Roland one week ago (still waiting for delivery). I assume (perhaps wrong?) that the 662 is used in this chain and can perhaps be the problem? They are not very expensive so i thought i might give it a shot

At the same time, i plan to exchange capacitors (as uncle krunkus suggested). I got all needed caps for the PSU (exact spec, only slightly smaller nowadays) and a load of caps for much of the rest. Soldering time soon...

Still waiting for the 662:s from Roland. In the meantime, i followed Uncle Krunkus advice and replaced some caps. I started with the big ones in the PSU and da-daaaaaa: No more hissing in the background Thank you U.K.

Some images follows

(ps. and after 3 months of waiting, finally my wooden sides decided to show up. They were purchased from Synthwood)

So how is the noise issue?
Something tells me it should be easier to trace it out than other possible faults on a Juno106. But I could be wrong. At least with the caps done, the noise source should stick out like the proverbial canine testes! _________________What makes a space ours, is what we put there, and what we do there.

Also looking for some information on fixing the noise generator - i own a Juno which is in perfect condition sans for the noise slider having absolutely no effect. If anyone's got any information it would be ridiculously helpful, cheers.

Also looking for some information on fixing the noise generator - i own a Juno which is in perfect condition sans for the noise slider having absolutely no effect. If anyone's got any information it would be ridiculously helpful, cheers.

Unkle and JC,

Still waiting for the 662:s from Roland (they had to order them from Denmark and it has taken more time than planned). I called the service center last week and they said they would ship on Friday (2 days ago). We'll see. I went back to the electronics store (ELFA in the european countries) and got me some more caps (might as well do as much as i can muster while i am opening it up again to replace the 662:s). I'll let you know if this solves the noice-issues. Stay tuned.

Well, i'm still at it. I finally got my voice-chips from D'naab in Belgium (analoguerenaissance.com) to fix my faulty number 6 voice (it emmited a weak tone in the background when the #6 voice was released). Ordered one extra just in case since i believe the rest of the Roland chips will soon start to act up as well.

Anyway, i managed to source a replacement for the noise generator transistor from a swedish company called "Elfa". The name/brand of this particular transistor is "NTE289A" in case anyone is interested. Afaik, this particular transistor is getting hard to source since they do not fulfill environmental directives (but again, there will probably be others that will and that matches the original....).

Long story short, i replace the original "NZ" transistor and.... didn't work

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